ST. LOUIS – It’s an old argument, but hardly a tired one, because it never goes out of style to hammer a bad idea. The designated hitter was a bad idea when it was introduced in 1973, it was a bad idea when it was introduced to the World Series on an alternate-year basis in 1976, it was a bad idea when it was used on an alternate-site basis beginning in 1986.

And it’s still a bad idea.

In fact, in some ways, it becomes worse the longer we have it on the books. So every once in a while, it’s good to have a situation like the one we’re going to have for Game 3, 4, and (if necessary) 5, during this year’s World Series.

It’s not good if you are the Boston Red Sox, entering these games at St. Louis’ Busch Stadium on as remarkable a roll as they’ve ever been, at any point in franchise history. Six straight wins, four of them knowing that one slip-up would end their season. And David Ortiz was an integral ingredient in every one of them.

But so was Kevin Millar. Without Millar’s walks in Games 4 and 5 against the Yankees, without his two-out double that led to an ice-breaking run off Jon Lieber in Game 6, where would the Red Sox be?

Terry Francona will find out soon enough.

Because for these games in St. Louis, he will have a decision to make: Who plays first base? Millar or Ortiz? Both of them are natural DHs. In a perfect world, Doug Mientkiewicz would be the Sox first baseman, because he is the one who actually knows how to play first base. But the Red Sox were built on offense, on weighing down the scoreboard with heavy run totals.

Millar plays first under that philosophy; Ortiz DHs. Maybe, in another year, Francona would have figured out an equitable way to distribute at-bats to both. But not the way Ortiz has been playing. You take Ortiz out of the lineup, you risk the wrath of 86 years, and you ought to have your head examined.

So Ortiz grabs a glove and plays first base, which is a little less painful on the eyes than listening to Carl Lewis sing the national anthem is on the ears. But only slightly.

And Millar goes to the bench.

How, exactly, is that fair?

“It’s not our best team out there,” Francona said last night. “It’s not the team we built to compete. That team was the one you saw in Boston. But, then, St. Louis didn’t build their team to have a DH in it. I guess you just have to try to minimize your problems and maximize your output, and make it less of a concern than it has to be.”

That’s a sporting thing for Francona to say, but it only underlines how offensively unfair the DH is at its root. The Cardinals are hardly at a disadvantage by sticking an extra bat in their lineup. But everything about the Red Sox lineup takes a hit. The Sox aren’t the first AL team to suffer such a quandary – remember Joe Torre’s famous Cecil Fielder-over-Tino Martinez choice in 1996 – but they may absorb the biggest hit.

“Those are the rules,” Millar said last night. “I sure as hell can’t argue with Papi playing over me, not the way he’s been playing. Without him, we’d be sitting home watching the Series at home. Watching in the dugout is better.”

The travesty of the DH has gone on long enough. Thirty-one years ago, baseball was a dying sport, its offensive numbers truly offensive, its pitchers so far ahead of its hitters as to be positively laughable. American League teams couldn’t draw and badly needed a gimmick. Now the Yankees draw nearly 4 million fans a year, and the Red Sox sell every seat.

The DH outlived its usefulness years ago. Now, as it intrudes on the World Series three straight days, it has become a full-blown nuisance. It has to go. The sooner the better.